Attachable Front for Eyeglasses

ABSTRACT

A removable attachment for eyeglasses, where the attachment, when mounted on a parent pair of eyeglasses, substantially completely covers the front and periphery of the parent frame, such that the combination appears to be a pair of dedicated sunglasses instead of ordinary eyeglasses with an attachment. The attachment is held to the parent eyeglasses by magnets. The bridge of the attachment includes ball joints that allow the attachment to fold for storage while not in use.

RELATED APPLICATIONS

This application claims the benefit under 35 USC §119(e) of the filingdate of U.S. Provisional Patent Application No. 62/125,872 entitled“Attachable Front for Eyeglasses”, filed Feb. 2 2015.

BACKGROUND OF THE INVENTION

For visual comfort outdoors, many people prefer eyeglasses with tintedlenses (commonly called “sunglasses”). For those who wear prescription(“Rx”) eyeglasses, this preference motivates the purchase of at leastone additional pair of eyeglasses. Since Rx eyeglasses are relativelyexpensive, and it is often inconvenient to carry a second pair, analternative has become popular; namely, the use of an attachable frontthat ‘clips onto’ the user's clear Rx spectacles (herein “parent”glasses). The attachable front preferably carries tinted lenses with nooptical power.

When in use, it is important that jostling does not inadvertently detachthe attachment from its parent. And for user convenience when not beingworn, it is preferred that the attachment can be stored compactly.

With prior art attachments, the considerations mentioned above causecosmetic/fit-up issues since, as dispensed, for each style of Rxspectacles the curvature of the eye openings of various pairs can differmarkedly from one to another. This variation arises because the threedimensional front curvature (the “base curve”) of a prescription lensdepends on its required optical performance, which varies substantiallyin the populace. Hence each eye opening of a frame into which Rx lensesare being installed must often be ‘reformed’ by the dispenser to enableproper lens positioning. For this reason Rx eyeglasses with prior artattachments usually have an obvious gap between the lenses of the parentand the lenses of the attachment, and hence do not have the appearanceof true sunglasses, looking instead like glasses with a double set oflenses. The gap between parent frame and attachment is not onlyunsightly, but also allows light leakage and troubling internalreflections.

The invented attachment described herein eliminates these deficiencies.In addition, while suitable for converting clear eyeglasses intosunglasses, the invented attachment is not limited to that use. Otherapplications include, for example, providing on-demand a second (orthird) optical power.

SUMMARY OF THE INVENTION

The invented attachment is described herein in the context of convertingclear Rx eyeglasses into Rx sunglasses (via zero optical power tintedlenses), but it will be understood that the invention is applicable aswell to attachments with lenses having optical power, tinted or not, forother applications.

For convenience, relative directions mentioned herein are stated withreference to a hypothetical standing eyeglass wearer. The term“frontward”, and similar, refer to the direction away from the wearer;“rearward”, and similar, refer to the direction toward the wearer;“downward”, and similar, indicate toward the earth. Other directions areto be taken consistent with the foregoing.

“Propellering” means an incidental twist along a horizontal axis of thefront of a frame (causing it to look somewhat like the propeller of anairplane); and “flapping” indicates an incidental bending, about avertical axis, of one eye opening with respect to the other. “Vertical”is the up/down direction with respect to a standing wearer.

As applied to a rim, the term “width” refers to a quasi-radialdimension; as applied to a magnet, this term refers to the as-installeddimension most nearly aligned with the width of the nearest portion ofthe rim. As applied to a portion of a rim, the term “length” refers to acircumferential direction; as applied to a magnet, the term “length”refers to the magnet's as-installed dimension in the direction alongthat circumference. As applied to a magnet, the term “thickness” refersto the magnet's as-installed dimension in the front/rear direction. Theterms “eyeglasses”, “glasses” and “spectacles” are used interchangeably.The term “lens” herein refers to a transparent lens-like item, whetheror not it has optical power, and whether or not it is tinted. And theterm “lens unit” refers to a lens and rim combination.

The preferred embodiment of the attachment as described herein iscomprised of two substantially identical lens units, except that each isthe mirror image of the other, connected by a bridge. In the presentlypreferred embodiment described herein, each lens unit is coupled to thebridge via a ball joint, thereby permitting the attachment to foldcompactly for ease in transport and storage. The term “ball joint” asused herein is meant to refer to a rotatable joint involving asubstantially spherical external surface that slidably mates with asubstantially spherical internal surface. The joint has essentially asingle degree of freedom, the primary rotation being about a verticalaxis. However, some limited motion about other axes is also possible.The substantially spherical surfaces are preferably either caps orsegments of a sphere.

The preferred method of latching the attachment to its parent frame isvia magnets that are attracted to the front face of the correspondingrim of a parent frame. Accordingly each rim of the parent frame ispreferably made of a ferromagnetic material; for example, type 430, 434or other 400 series stainless steel. Alternatively, the rim of theparent frame may be made of plastic with a ferromagnetic insert orinlay. The attachment includes a plurality of preferably rare earthmagnets preferably disposed along the quasi-vertical outboard edge ofeach lens unit. The term “quasi-vertical” means that a member'sorientation has a vertical component greater than its horizontalcomponent. The presently preferred number of magnets is four peroutboard edge, but other numbers may be used. To best achieve theadvantages of the present invention, no fewer than two magnets should beincluded in each outboard edge of a lens unit.

The magnets in the attachment preferably have frontal dimensions which(in the radial direction) are larger than the corresponding dimensionsof the mating parent frame (or the magnetic insert in the case of thealternate construction disclosed), and the attachment preferablyincludes ‘skirts’ which extend primarily rearward from its frontsurfaces and cover the parent frame (completely, or partially). The term“cover” (including its variants) is intended to refer to the overlap ofthe attachment with respect to the parent frame. Compared with prior artattachments, these skirts (including the corresponding portions of theattachment bridge) are deeper and more comprehensive. For this reason,when in use, the attachment truly envelops the entire (or at least mostof the) front of its parent frame, thereby i) hiding substantially allof the parent frame's visual aspects (including the parent bridge), andii) presenting (other than at the temples) no gaps between theattachment and the front of its parent, which would otherwise be visiblewhen observing the wearer from his/her front, top, or side. Thiseliminates light leakage, and also actually transforms the appearance ofthe parent frame into that of a sunglass. Alternatively, the skirtscould extend rearward to cover only a portion of the depth of the parentlens units. This latter construction, while perhaps not as attractive asthe first embodiment described above, still eliminates the undesirablevisual gap between the attachment and the parent frame.

Adequate magnetic latching without regard to the base curve of thelenses installed in the Rx parent frame is addressed, in part, bylocating the magnets within or along the quasi-vertical outboard edgesof the attachment (instead of, as is common in some prior art, within oralong the quasi-horizontal edges). This provides a significant benefitbecause the variation in curvature along an eye opening is usually muchless when viewed from the side than when viewed from the top.

Robust magnetic latching is further achieved by a magnet array thatprovides adequate latching force even when the rim of the correspondingparent frame deviates from its nominal as-manufactured location. Astouched on previously, such deviation can arise from manufacturingtolerances, or from reforming the parent to accommodate specific Rxlenses (which can change not only curvatures but also the horizontaldimension between the outboard edges of the two lens units), or fromwearer abuse.

The present invention utilizes magnet arrays which have a preferrednominal width that is at least 120% of the nominal width of the parentframe eyewire (or, correspondingly, the width of the alternativemagnetic insert). As a consequence of the ball joints, it also providesunique mechanical compliance in the ‘flapping’ and ‘propellering’directions. If desired to improve resistance to incidental shock in use,a downward-extending lip positioned behind the parent bridge may also beprovided.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of one embodiment of the inventedattachment latched onto a parent frame.

FIG. 1A is a view of the invented attachment similar to FIG. 1, exceptthat the parent frame is shown separated from the attachment.

FIG. 2 is a rear view of one embodiment of the invented attachment.

FIG. 3 is a vertical cross sectional view of the bridge of theembodiment shown in FIG. 1 taken at 3-3 of FIG. 1. For clarity, only thecutting plane is shown.

FIG. 4 is a vertical cross sectional view of one of the lens units ofthe embodiment shown in FIG. 1, taken at 4-4 of FIG. 1. For clarity,only the cutting plane is shown.

FIG. 4A is a view similar to FIG. 4, but showing a different rim design.

FIG. 5 is a top fragmentary exploded view of the central portion of theembodiment shown in FIG. 1, showing the connection between the lensunits and the bridge.

FIG. 6 is a rear fragmentary, partly sectioned, exploded view of thecentral portion of the embodiment shown in FIG. 1, showing theconnection between the lens units and the bridge. The section is takenat 6-6 of FIG. 5.

FIG. 7 is an oblique fragmentary view of one lens unit showing detailsof the connection to the bridge.

FIG. 8A is an oblique sectioned view of one form of bridge.

FIG. 8B is an oblique sectioned view of a second form of bridge.

FIG. 9 is a rear fragmentary view of a lens unit showing a plan view ofthe magnet pockets.

FIG. 10 is a fragmentary sectioned view of a lens unit taken at 10-10 ofFIG. 9.

FIG. 11 is an enlarged view of one of the magnet pockets of FIG. 10,without a magnet installed.

FIG. 12 is a view similar to FIG. 1A, but of a second embodiment.

FIG. 13 is a view similar to FIG. 1A, but of a third embodiment.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS OF THE INVENTION

The perspective view of FIG. 1 shows a first embodiment of the inventedattachment 11 as it is intended for use, installed on a parent frame 50.FIG. 1A shows the same attachment 11, with a parent frame 50, butseparated. The preferred means of attaching is by magnetic attractionbetween magnets carried by the attachment lens units 24, and the rims 51of the parent frame. The parent frame rims 51 in this first preferredembodiment are preferably fabricated from a ferromagnetic material suchas, for example, type 430 stainless steel.

As can be seen in FIG. 1A, the invented eyeglass attachment includes twolens units 24 and a bridge 12. For clarity both lens units are numbered24, even though they are not actually identical but rather are mirrorimages of each other. Also, the bridge is denoted as 12, indicatingeither one of the two somewhat different bridge designs described. Otherbridge designs within the present invention are also contemplated. Eachlens unit 24 is comprised of a rim 13, a lens 14, and (as can be seen inFIG. 2) a plurality of magnets, 22. Depending on the intendedapplication, the lenses may or may not have optical power, and also mayor may not be tinted.

Referring to FIGS. 3 and 4 it can be seen that the attachment rims 13,and bridge 12, also include skirts (25, 26) of sufficient depth thatwhen the attachment is mated to its parent, other than at the temples nopart of the parent frame is (preferably) visible to onlookers. Thisoffers cosmetic benefit and also eliminates the possibility of lightintrusion between the attachment and its parent. Alternatively, onlysome, but not all, of the parent frame's depth is covered. Thisalternative construction is illustrated in FIG. 4A, where skirts 26A canbe seen as covering only a portion of rim 51.

The attachment rims 13 are coupled to the bridge 12 through tongues 15(FIGS. 5 and 6). Each tongue 15 includes projections 16 (from the topand bottom of the tongue), each preferably shaped in the form of asegment of a sphere. For ease of assembly, each projection is preferablytruncated, resulting in a small flat top. The illustrated truncationsare only a convenience, however, and may not, in all cases be necessaryor desired (that is, the projections may have surfaces representingeither segments or caps of a sphere). While not presently preferred,each tongue could have only one projection (e.g., on the top of eachtongue, or on its bottom).

The spherically shaped projections 16 (whether segments or caps) matewith spherically shaped recesses 17 in the bridge 12 to form ball joints16/17. The tongues and ball joints permit the attachment to fold forstorage when not in use, and also provide mechanical compliance tofacilitate magnetic latching to a parent which may be somewhat deformedin the propellering and/or flapping directions. The rims and the bridgeof the attachment are preferably molded from suitable plastic materials,for example, nylon. As shown, for example, in FIGS. 6, 8A and 8B thebridge 12 preferably includes a septum 27. The septum serves to increasethe stiffness of the flanges of Bridge 12 which form recesses 17, andthereby improve the “feel” in the user's hand, of ball joints 16/17. Thewidth of the septum is preferably in the range of 0.02″ to 0.09″.

As implied by FIGS. 8A and 8B (which show alternate constructions) wheninstalled on a parent frame, feature 18 on the bottom of bridge 12 fitsover and in front of bridge 52 of the parent frame. Optional lip 19depends from the bridge and fits behind parent bridge 52 so as to retainthe attachment in the event that the magnetic retention is transientlyovercome by a very strong shock.

FIGS. 9, 10, and 11 illustrate the preferred magnet array. The followingdescribes the presently preferred magnet array configuration, however,many other magnet array configurations are possible, which arrangementswill result in varying magnetic latching forces, depending on thearrangement. While designing to achieve adequate magnetic latching withthe parent frame, (understanding that the parent frame may have to bedeformed from its as-manufactured shape and hence cannot fit snuglyagainst the magnet-bearing region of the attachment), conflictingrequirements arise. We have found that adequately strong latching can beachieved, despite a somewhat reduced magnet mass which might otherwisebe installed near each quasi-vertical outboard edge, by a) dividing theregion, into which magnets are to be emplaced, into discrete andmore-or-less collinear pockets, each separated from the next by anon-magnetic wall; b) poling each magnet through its thickness, and c)mounting the magnets to expose alternating North and South poles to theeyewire along the length of the array. In the resulting magnet array theinter-pocket walls each provide two primary functions: i) they set aspecific gap between each North/South pole pair, thereby forcing themagnetic field spanning this gap to extend relatively deeply into theadjacent space (which enables onset of latching force even when theparent is reasonably distant); and ii) they create pockets, each ofwhich are adequately stiff to retain a magnet by friction (i.e., withoutneed for adhesive). The inter-magnet gaps also establish multiplelatching locations, which can itself be a benefit. Another benefit isthe ability to manufacture the attachment without use of adhesives.Preferred inter-pocket wall spacing depends on the dimensions of, andmaterial from which, the magnets are manufactured, and also on the resinfrom which the attachment is molded. Generally speaking this spacing ispreferably more than about 0.003″, and less than about twice thethickest magnet thickness. More preferably the magnets are spaced in therange of 0.01″ to 0.03″.

FIGS. 9 and 10 illustrate a preferred magnet array. In this case thepreferred number of magnets is four, but other configurations of parentframe {and, hence, corresponding configurations of attachment} couldfavor use of another number, perhaps two to six. An even number ofmagnets is preferred, but not essential. Each magnet is preferably ofthe rare earth type, and even more preferably made from NdFeB grade N48or N52 material. FIG. 11 shows a typical magnet pocket before a magnethas been installed. Each magnet pocket 20 (see FIG. 11) is preferablysized such that a magnet 22 may be pressed in without breakage, and yetwill be retained by frictional forces.

To assure that they do not scratch the rim of a mated parent frame (andyet not substantially reduce magnetic latching energy), the exposed faceof each magnet is preferably located slightly below the adjacent rearsurfaces of its corresponding pocket. In FIG. 10 this distance is shownexaggerated for clarity; it is preferably in the range of 0.0003″ to0.0012″. A small groove 21 (which can best be seen in FIG. 11) ispreferably molded into the wall or at a corner of each magnet pocket, sothat air may escape from below each magnet when it is being pressed intoplace.

As mentioned above, the distance between the outboard quasi-verticaledges of multiple instances of a given style of parent frame is subjectto variation, in part because of manufacturing tolerances but alsobecause dispensers reform parent rims to accommodate Rx lenses havingdifferent base curves. Accordingly, best to act in conjunction with thegaps in each magnet array, each magnet 15 should have a width somewhatwider than the width of the intended parent rim. That is, the magnets 15preferably should have a width of at least 120% of the nominal facewidth of the rim of the intended parent frame (or inlay, as the case maybe), and more preferably a width in the range of 120% to 150%.

In order to illustrate the design flexibility of the present invention,a somewhat different stylistic design of the parent and attachment isshown in FIGS. 12 and 13.

FIG. 12 illustrates a second embodiment of the invention wherein theparent frame rims, instead of being fabricated primarily from metal, arefabricated primarily from a suitable plastic material, such as, e.g.,nylon. In order to provide a magnetic latching force, strips offerromagnetic material (151), such as type 430 or 440 stainless steelare inlayed into the outboard vertical portions of the rims, located tomatch the locations of the magnets in the mating attachment.

FIG. 13 shows yet another embodiment of the invention wherein theferromagnetic strips (251), rather than being inlayed in the rims, areembedded therein, so as to not be visible in the final product. For bestresults, the strips are preferably embedded with their front surfaces0.010 inches or less below the rim front surface.

While the presently preferred embodiments of the invention have beendescribed above, persons of skill in the art will realize that theinvention, as claimed in the appended claims, can be practiced eventhough some particulars may be changed to suit particular circumstances.Such changed embodiments as fall within the terms of the claims or areequivalents thereof are intended to be covered hereby.

We claim:
 1. An attachment for eyeglasses that comprises: a pair of lensunits, each said lens unit including a lens and a rim, said lens unitsbeing coupled together through one or more ball joints, at least one ofsaid ball joints having a primary axis of rotation, said primary axis ofrotation being the vertical, whereby said attachment is foldable.
 2. Anattachment for eyeglasses as recited in claim 1 wherein the rim of atleast one of said lens units has a tongue projecting therefrom, saidtongue having one or two substantially spherically shaped externalsurface(s) thereon, said substantially spherically shaped externalsurface(s) being either segments or caps of a sphere.
 3. An attachmentfor eyeglasses as recited in claim 2 and further including a bridge, andwhere said substantially spherically shaped external surface(s) slidablymate with corresponding substantially spherically shaped internalsurface(s) within said bridge.
 4. An attachment for eyeglasses asrecited in claim 1 wherein said attachment is intended for attachment toa parent pair of eyeglasses, and where said parent pair of eyeglassesand said attachment each include a bridge, and where said bridge on saidattachment includes a downwardly directed lip that engages said parentbridge behind said parent bridge to prevent said attachment from beingdislodged when said glasses are jostled.
 5. An attachment for eyeglassesas recited in claim 1 where both said rims and said bridge are injectionmolded plastic.
 6. An attachment for eyeglasses that comprises, a pairof lens units, each said lens unit including a tongue projectingtherefrom, each of said tongues having one or two substantiallyspherically shaped external surfaces thereon; and a bridge positionedbetween said lens units, said bridge including two or four substantiallyspherically shaped internal recesses, said substantially sphericallyshaped external surfaces each slidably mating with a corresponding oneof said spherically shaped internal recesses.
 7. An attachment foreyeglasses as recited in claim 6 wherein said substantially sphericallyshaped surfaces are either segments or caps of a sphere.
 8. Eyeglassesand an attachment therefore which comprises: eyeglasses including afirst pair of lens units held in spaced relationship by a first bridge,said first pair of lens units having first rims, and temples attached tosaid first rims; and an attachment for said eyeglasses, including asecond pair of lens units each having a second rim, said lens unitsbeing held in spaced relationship by a second bridge, said second pairof rims including skirts that, when said attachment is installed on saideyeglasses, cover at least a portion of the depth of said first rimsaround the entire periphery of said first pair of lens units except atthe temples and at the second bridge, said second bridge covering atleast a portion of the depth of said first bridge.
 9. Eyeglasses and anattachment therefore as recited in claim 8 wherein said skirts on saidsecond rims cover all of the depth of said first rims around the entireperipheries of said first pair of lens units, except at the temples andat the bridge, and said second bridge covers at least most of the depthof said first bridge.
 10. Eyeglasses and an attachment therefore asrecited in claim 8 wherein said attachment is foldable.
 11. Eyeglassesand an attachment therefore as recited in claim 8 wherein the front faceof each of said first rims is magnetically attractive over at least aportion of the rim circumference, and wherein each of said second pairof rims includes at least two magnets secured to each of said secondrims and positioned to face the magnetically attractive portions of saidfront faces of said first rims when said attachment is mounted on saideyeglasses, the poles of said magnets facing said first rims, the faceof one of each pair of magnets facing said first rims being poled north,and the face of the other of each pair of magnets facing said first rimsbeing poled south.
 12. Eyeglasses and an attachment therefore as recitedin claim 11 wherein the magnets of each pair are spaced apart at leastabout 0.003 inches, and up to an amount equal to about twice thethickness of the thickest of said pair of magnets.
 13. Eyeglasses and anattachment therefore as recited in claim 11 wherein each of said rimshas a quasi-vertical outboard edge, and said magnetically attractiveportions and said magnets are positioned along said quasi-verticaloutboard edges.